The invention relates to an apparatus for supporting cables and a transportation installation with aerial cables comprising an apparatus of this type.
An apparatus for supporting cables intended for a transportation installation having two carrying and pulling aerial cables, comprising a tower, a bracket supported by the tower and balance-beams equipped with rollers over which the cables travel, supported by the bracket, is already known (European Pat. No. 93 680). More precisely, this known apparatus comprises basic balance-beams which, for each cable, comprise a flat bar on which two rollers are mounted, the two flat bars of the two cables being connected rigidly to each other by virtue of a rigid stirrup member. This basic balance-beam constitutes a non-deformable, one-piece arrangement mounted to pivot by its flat bars about a point at right angles to the cables on small girders themselves mounted to pivot. The main structural feature of this known apparatus is that on the one hand the spacing of the rollers corresponding to two cables is kept positively constant and equal to the spacing of the cables and that on the other hand, the pivoting movements of all the rollers (about the pivot point of the flat bars) corresponding to the two cables are carried out positively in perfect synchronism, that is to say that symmetrical pivoting of the balance-beams is imposed. Maintaining the spacing and synchronism positively as well as the symmetry of the pivoting is obtained by virtue of the rigid stirrup member making the rollers (or more precisely their axes of rotation) arranged to correspond and associated with the two cables into a one-piece and non-deformable arrangement. Taking into account the passage which has to be left free between the cables for the carriage or the like supporting the vehicle, the stirrup member is in the general shape of an inverted U. This known structure responds to the necessity of ensuring perfect symmetry and synchronism between the two cables and thus the members which are associated therewith. If from the theoretical point of view, this necessity seems legitimate, it is not so from the practical point of view. In fact, despite the care taken with a view to giving the cables the same physical parameters (in particular length, speed, tension, etc.), in practice these parameters may vary considerably from one cable to the other on the same cross section, if only owing to the fact that the paths of the cables are separate from each other (the paths possibly being varied overall) with all the resulting consequences. Under these conditions, maintaining the synchronism or symmetry of movement between the balance-beams or rollers may in fact prove to be a particularly troublesome drawback to the extent that it produces additional stresses in the apparatus for supporting cables.